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Dyschromatosis universalis hereditaria
Dyschromatosis universalis hereditaria (DUH), OMIM 127500, is a rare hereditary genodermatosis with mottled hyper- and hypopigmented macules from infancy; genes ABCB6, SASH1, KITLG; no curative treatment.
Dysembryoplastic neuroepithelial tumor
Dysembryoplastic neuroepithelial tumor (DNET/DNT), a benign WHO grade I glioneuronal brain tumor first described in 1988, typically causing drug-resistant focal epilepsy in children and young adults, mostly in the temporal lobe.
Dysentery
Dysentery is bloody, mucoid diarrhea from intestinal invasion, mainly bacillary (Shigella) or amoebic (Entamoeba histolytica). Key facts: fecal leukocyte counts, Shigella mortality OR 3.9, antibiotic and amoebicide treatment, dysentery as a poor Shigella marker.
Dysesthesia
Dysesthesia, an unpleasant abnormal sensation defined by the IASP, distinct from paresthesia; includes allodynia and hyperalgesia, occurs in neuropathic pain, skin and neurological disorders, with causes, diagnosis, and treatments.
DYSF
DYSF (FER1L1) is the human gene on chromosome 2p13.2 encoding dysferlin, a ~240 kDa ferlin-family protein with seven C2 domains that repairs the muscle sarcolemma; mutations cause dysferlinopathies (LGMD2B/R2, Miyoshi myopathy, DMAT).
Dysferlin-related limb-girdle muscular dystrophy R2
Dysferlin-related limb-girdle muscular dystrophy R2 (LGMDR2, formerly LGMD2B) is an autosomal recessive dystrophy caused by DYSF mutations, with proximal weakness from the late teens, very high CK, and possible cardiac involvement.
Dysfunctional family
A dysfunctional family, also called family dysfunction, is a family whose impaired relationships or communication keep members from achieving intimacy, often handing dysfunction down through generations.
Dysgeusia
Dysgeusia is a taste disorder in which taste is distorted, so a foul, salty, rancid, or metallic taste persists in the mouth; it is distinct from ageusia, the complete loss of taste.
Dysgraphia
Dysgraphia, also called disorder of written expression, is a neurological learning disorder causing writing difficulty despite adequate instruction. Estimated 5-20% prevalence; treated with remedial education, occupational therapy, and accommodations.
Dyshidrosis
Dyshidrosis (dyshidrotic eczema, pompholyx): recurrent itchy 1–2 mm tapioca-like vesicles on palms, finger sides, and soles, clearing in 2–3 weeks; cause unknown, linked to atopy, nickel/cobalt allergy, and hyperhidrosis.
Dyskeratosis congenita
Dyskeratosis congenita (Zinsser–Engman–Cole syndrome) is a rare inherited telomere biology disorder causing very short telomeres, the mucocutaneous triad of nail dystrophy, reticular pigmentation, and oral leukoplakia, plus bone marrow failure and cancer risk.
Dyskinesia
Dyskinesia: involuntary abnormal movements, chiefly tardive dyskinesia from dopamine receptor blocking agents (24–32% with older antipsychotics) and levodopa-induced dyskinesia in Parkinson's disease; treated with VMAT2 inhibitors valbenazine and deutetrabenazine.
Dyskinetic cerebral palsy
Dyskinetic cerebral palsy (athetoid, dystonic CP; ICD-11 8D21): CP subtype with involuntary movements and dystonia from basal ganglia/thalamus injury; 6-15% of CP cases, second most common after spastic CP.
Dyskolos
Dyskolos (Δύσκολος, often translated The Grouch) is a comedy by the Athenian playwright Menander, first performed in Athens in 316 BC and his only surviving complete play.
Dyslexia
Dyslexia is a neurodevelopmental learning disability affecting word reading and spelling, first named by Rudolf Berlin in the 1880s; prevalence estimates range from 5 to 17.5 percent, with phonological processing deficits as the leading marker.
Dyslexia or alexia
Dyslexia or alexia (ICD-11 MB4B.0) is the acquired loss, usually in adulthood after stroke or brain injury, of previously fluent reading and comprehension, distinct from developmental dyslexia; syndromes include pure, surface, phonological, and deep dyslexia.
Dyslipidemia
Dyslipidemia: abnormal blood lipid levels (high cholesterol, high triglycerides, high Lp(a), or low HDL-C), also called hyperlipidemia. Causes are genetic or secondary; treatment is lifestyle plus statins, guided by 2026 ACC/AHA PREVENT-based risk thresholds and LDL-C goals.
Dysmenorrhea
Dysmenorrhea, or painful menstrual periods, affects 50–90% of young women. Primary dysmenorrhea (about 90% of cases) stems from uterine prostaglandins; secondary forms arise from endometriosis, adenomyosis, or other pelvic pathology. NSAIDs and hormonal contraceptives are first-line treatments.
Dysmenorrhoea
Dysmenorrhoea, or dysmenorrhea, is painful menstruation, classified as primary (no pelvic pathology) or secondary (caused by conditions such as endometriosis). Prostaglandin-driven uterine hypercontractility causes the pain; NSAIDs and combined oral contraceptives are first-line treatments.
Dysnomia (moon)
Dysnomia is the only known moon of the dwarf planet Eris, discovered in 2005 and named for the Greek goddess of lawlessness, daughter of Eris.
Dyson (company)
Dyson, also known as Dyson Limited, is a British technology company founded by Sir James Dyson, best known for bagless cyclonic vacuum cleaners and now selling hair care and air treatment products.
Dyson Daniels
Dyson Daniels (born 2003, Bendigo, Australia) is an Atlanta Hawks guard, No. 8 pick in 2022 via G League Ignite; 2024-25 steals leader (229), Most Improved Player, All-Defensive First Team, $100M extension.
Dyson equation
The Dyson equation is the integral equation of quantum field theory relating the full interacting Green's function to a reference one and the self-energy, introduced by Freeman Dyson in 1949.
Dyson sphere
A Dyson sphere, also called a Dyson shell or Stapledon sphere, is a hypothetical megastructure around a star collecting its energy, proposed by Freeman Dyson in 1960.
Dyson's eternal intelligence
Dyson's eternal intelligence is a speculative scenario proposed by Freeman Dyson in 1979 under which intelligent life in an ever-expanding, ever-cooling universe could continue thinking forever using only finite energy, by slowing metabolism and hibernating.
Dysosteosclerosis
Dysosteosclerosis (DSS, DOS; OMIM 224300) is an ultrarare genetic bone dysplasia with progressive osteosclerosis and platyspondyly, an osteoclast-poor osteopetrosis-like disorder linked to SLC29A3, TNFRSF11A, TCIRG1, LRRK1, and CSF1R, with fewer than 30 reported cases.
Dyspareunia
Dyspareunia is recurrent pain with vaginal intercourse, superficial (introital) or deep, affecting up to 3 of 4 women at some point; causes include vulvodynia, endometriosis, and menopausal atrophy.
Dysphagia
Dysphagia, difficulty swallowing, is classified as oropharyngeal or esophageal. Prevalence 10–20%; linked to stroke pneumonia risk (RR 3.17); assessed by VFSS, FEES, endoscopy, and manometry.
Dysphagia lusoria
Dysphagia lusoria (Bayford syndrome) is difficulty swallowing from esophageal compression by an aberrant right subclavian artery, a congenital aortic arch anomaly in 0.5-2.5% of people, mostly asymptomatic.
Dysphagia screening
Dysphagia screening is a rapid bedside pass/fail procedure, standard in acute stroke care, that identifies patients at risk of swallowing difficulty before any oral intake.